1. Field of the Invention
The present invention relates to a semiconductor device and a method and apparatus for manufacturing a semiconductor device, and, particularly, to a nitride compound semiconductor device and a method and apparatus for manufacturing the nitride compound semiconductor device.
2. Description of the Related Art
In recent years, semiconductor compounds having a large bandgap, such as AlN, GaN, AlGaN, GaInN and InN, have attracted considerable attention as materials such applications as blue LEDs, blue LDs and visible light-emitting elements. In the production of these nitride-type group IIIA (Group number 13 in a revised edition of Inorganic Chemistry Nomenclature in 1989 by IUPAC (International Union of Pure and Applied Chemistry))-VA (Group number 15 in a revised edition of Inorganic Chemistry Nomenclature in 1989 by IUPAC) semiconductor compounds, NH3 gas or N2 gas is used as the VA element source. These NH3 gas and N2 gas are however more stable and hence more inactive than the VA element sources, e.g., AsH3 gas and PH3 gas which are used in the production of other III-V compound semiconductors. When a film of the nitride-type III-V semiconductor compound is formed on a substrate by a metal organic chemical vapor deposition method (MOCVD), the temperature of the substrate is therefore adjusted to 900 to 1200xc2x0 C.
The materials which can be used at this substrate temperature are, however, limited. Bulk crystal substrates which are usually used for III-V compound semiconductors, e.g., GaAs, cannot be used but expensive substrate materials such as sapphire and SiC crystal are used. However, almost no In is incorporated into crystals at substrate temperatures as high as 900 to 1200xc2x0 C. at which GaN of high quality grows and hence the substrate temperature is lowered in the production of mixed crystals containing In. In this method, however, the film quality of a compound semiconductor is sacrificed and it is therefore difficult to obtain a high quality mixed crystal containing 10% or more of In. Also, the method of changing the substrate temperature, when a film is formed at high temperatures, may cause, for instance, the diffusion of elements in the film formed at low temperatures and it is therefore difficult in practice to produce multi-layer film or super lattice elements.
To make growth at low temperatures, there is a method in which NH3 gas or N2 gas used as a VA element source is made into the form of plasma by glow discharge (J. M. Van Hore et al., J. Cryst. Growth 150 (1995) 908), microwave discharge, or electron cyclotron resonance and an organic metal compound containing a IIIA element is introduced into the remote plasma to form a film (A. Yoshida, New Functionality materials, Vol. C. 183-188 (1993), S. Zembutsuet al., App. Phys. Lett. 48, 870). It is reported that the formation of a GaN film using this method at temperatures between 600 and 900xc2x0 C. results in the production of crystals exhibiting a strong UV photoluminescence when the film is formed at 900xc2x0 C. (Tokuda, Wakahara, Sasaki, Shingaku Technical Report ED, 95-120p 25 (1995-11).
Well-known apparatuses for the production of a semiconductor device using this type of remote plasma include those comprising one activating means connected to a reactor, a first supply means for supplying the element source of the group VA, e.g., N2 gas to the activating means from the side opposite to the reactor and a second supply means for supplying an organic metal compound containing a IIIA element to the reactor side of the activating means.
It is, however, reported that, in the crystals grown at temperatures as low as 600xc2x0 C. or less using such an apparatus for the production of semiconductor devices, the crystallinity is reduced and hence only peaks from a deep level are observed. An increase in the amount of the raw materials to improve the growth rate results in the inclusion of a large amount of hydrogen in the film bringing about a further reduction in the crystallinity. Moreover, when a mixed crystal is produced using this apparatus for production of semiconductor device, a mixed gas containing two or more organic metal compounds, for example, trimethylgallium and trimethylindium is supplied by the second supply means. However, since the binding energies of these organic metal compounds differ from each other, one of either of these metal compounds tends to be selectively decomposed when these compounds are introduced into the plasma, giving rise to the problems that, even if the ratio of the two compounds in the mixed gas is regulated, the composition of the resulting film is controlled with difficulty, the crystallinity of the mixed crystal film is reduced and carbon impurities derived from the more undecomposable organic metal compound get mixed in the resulting film.
The cause of these problems is considered to be in the fact that, at such low temperature conditions that the raw material of the organic metal compound containing the IIIA element which takes a three-coordinate form in a gaseous state has difficulty in decomposing, releasing, and rearranging on the growth surface, the IIIA element either remains on the growth surface in the three-coordinate state while it contains hydrogen or is left as an element having a binding defect in the film as it has difficulty forming a four-coordinate network with a nitrogen atom.
An object of the present invention is to improve these drawbacks of the conventional method and apparatus using this type of a remote plasma for the production of a semiconductor device and to provide a method and apparatus for producing a semiconductor device having high quality and performance at a low temperature efficiently and also to provide a semiconductor device produced using these method and apparatus.
The inventors of the present invention have made earnest efforts and, as a result, have found that it is possible to produce a microcrystal film and crystal film having high quality by controlling a film forming step and reaction step using plasma and repeating a step of the formation of a IIIA element/nitrogen layer from an activated IIIA element atom and an activated nitrogen atom, and a step subsequent to this type of growth of a nitrogen layer containing nitrogen or nitrogen and hydrogen, a step of the passivation of defects and a step of the extraction of hydrogen, thereby solving the above problem, to complete the present invention. The present invention is characterized in that crystal growth is forwarded while the growth surface of a binding layer formed of a IIIA element atom and a nitrogen atom is restored and grown by the aid of a nitrogen atom and a hydrogen atom.
Accordingly, the features of the present invention to solve the aforementioned problem reside in:
 less than 1 greater than  A semiconductor device produced by forming a film of a nitride compound on a substrate having heat resistance at 600xc2x0 C. or less, wherein the nitride compound includes one or more elements selected from group IIIA elements of the periodic table and a nitrogen atom and produces photoluminescence at the band edges at room temperature;
 less than 2 greater than  A semiconductor device according to  less than 1 greater than , wherein the substrate is constituted of a base material selected from the group consisting of an electroconductive material, a semiconductor material and an insulating material;
 less than 3 greater than  A semiconductor device according to  less than 1 greater than , wherein the substrate is transparent;
 less than 4 greater than  A semiconductor device according to  less than 2 greater than , wherein the substrate is transparent;
 less than 5 greater than  A semiconductor device produced by forming a film of a nitride compound on a substrate having heat resistance at 600xc2x0 C. or less, the nitride compound including one or more elements selected from group IIIA elements of the periodic table and a nitrogen atom, wherein the absorption wavelength for the nitride compound in an infrared absorption spectrum ranges between 3000 cmxe2x88x921 and 700 cmxe2x88x921;
 less than 6 greater than  A semiconductor device according to  less than 5 greater than , wherein the absorption wavelength for the nitride compound in an infrared absorption spectrum further ranges between 700 cmxe2x88x921 and 400 cmxe2x88x921 and the ratio (Ia/Ib) of the maximum absorbance (Ia) in a wavelength range between 3000 cmxe2x88x921 and 700 cmxe2x88x921 to the maximum absorbance (Ib) in a wavelength range between 700 cmxe2x88x921 and 400 cmxe2x88x921 is 0.01 or more;
 less than 7 greater than  A semiconductor device according to  less than 5 greater than , wherein the substrate is opaque and the semiconductor device is used as a photovoltaic element;
 less than 8 greater than  A semiconductor device according to  less than 1 greater than , wherein the nitride compound is a mixed crystal of two or more semiconductor compounds;
 less than 9 greater than  A method for producing a semiconductor device, the method comprising continuously activating a nitrogen compound while introducing an organic metal compound containing one or more elements selected from group IIIA elements of the periodic table intermittently in the activated environment, to form a film of a nitride compound containing nitrogen and the group IIIA elements on a substrate;
 less than 10 greater than  A method for producing a semiconductor device according to  less than 9 greater than , wherein hydrogen or a compound containing hydrogen is further added to the activated environment;
 less than 11 greater than  A method for producing a semiconductor device according to  less than 9 greater than , wherein the organic metal compound comprises two or more organic metal compounds containing different group IIIA elements and the nitride compound is a mixed crystal of two or more semiconductor compounds;
 less than 12 greater than  A method for producing a semiconductor device according to  less than 11 greater than , wherein the two or more organic metal compounds are introduced intermittently at the same time;
 less than 13 greater than  A method for producing a semiconductor device according to  less than 11 greater than , wherein the two or more organic metal compounds are introduced intermittently so as not to overlap each other in time;
 less than 14 greater than  A method for producing a semiconductor device according to  less than 9 greater than , wherein a raw material for pn control is further added to the activated environment;
 less than 15 greater than  A method for producing a semiconductor device according to  less than 9 greater than , wherein glow discharge using radio frequency and/or glow discharge using microwave for the activation of the nitride compound;
 less than 16 greater than  A method for producing a semiconductor device according to any one of  less than 9 greater than  to  less than 15 greater than , wherein the temperature at which the film is formed on the substrate is 600xc2x0 C. or less;
 less than 17 greater than  A method for producing a semiconductor device, the method comprising continuously activating a nitrogen compound, continuously and separately activating an assistant material which is different from the nitrogen compound simultaneously and introducing an organic metal compound containing one or more elements selected from group IIIA elements of the periodic table intermittently in the environment in which the assistant material is activated, to form a film of a nitride compound containing nitrogen and the group IIIA elements on a substrate;
 less than 18 greater than  An apparatus for producing a semiconductor device comprising a reactor for forming a film of a nitride compound on a substrate; a heating and supporting means provided in the reactor for supporting and heating the substrate; a first supply means for supplying a first raw gas; a first activating means for activating the supplied first raw gas, the first activating means being connected to the first supply means and the reactor; and a second supply means for supplying a second raw gas intermittently to the reactor;
 less than 19 greater than  An apparatus for producing a semiconductor device according to  less than 18 greater than , further comprising a third supply means for supplying a third gas and a second activating means for activating the supplied third gas, the second activating means being connected to the reactor and the third supply means; and
 less than 20 greater than  An apparatus for producing a semiconductor device according to  less than 19 greater than , further comprising a fourth supply means for supplying a fourth raw gas to the reactor side of the second activating means, wherein the second supply means connects to the reactor side of the first activating means.